The use of fluid to perform various functions in the manufacturing and processing of electronic components such as printed circuit boards is well known. For instance, fluids are used to etch away certain portions of multi-layer circuit boards for example. The fluid treatment of electronic devices often involves immersing the devices in the treating fluid. However, the fluid in such treating baths is usually stagnant and, therefore, the fluid adjacent the device being treated often becomes saturated with the material being removed from the device. Saturation of the fluid decreases the amount of material which is removed from the device by an amount of fluid, decreasing the efficiency of the process and increasing the amount of fluid required to treat a substrate with a given area.
In order to avoid the problems associated with stagnant, saturated fluid next to the substrate being treated, devices were developed to direct fluid flow onto the surface of the electronic substrates being treated. Although these devices provide for improved process speed and uniformity compared to the previously known devices, and at least partially minimized chemical usage in environmental impact, such devices still produce regions in which the processing liquid is relatively stagnant.
In areas of stagnant fluid, such as the interiors of holes in substrates, whatever fluid reaches such areas tends to be retained on or in these areas (a phenomenon called puddling). Relatively little fresh fluid reaches these areas. Moreover, sprays often re-deposit or re-position, rather than remove, debris on the substrate, which then requires the use of additional sprays. Consequently, the use of sprays often requires the use of an undesirably large amount of processing area, which is also uneconomic. While attempts have been made to orient sprays to achieve directionality and thereby overcome some of the above-mentioned disadvantages, these attempts have typically been accompanied by a torque being imposed upon the substrate by the directed spray. This results in instabilities in the motion of the substrate, often causing jamming of the substrate in the corresponding processing equipment, resulting in damage to the substrate or equipment, which is undesirable and counterproductive.
As stated above, the reaction in areas of stagnant fluid may be reduced since fresh chemical is not replenished as rapidly. Also, particles contaminants can build-up in these regions which cause defects in the devices being processed. All of these problems with the prior art can result in a reduction in the uniformity of the process.